Phage Biocontrol of Pseudomonas aeruginosa in Water.

Ari Kauppinen,Sallamaari Siponen,Tarja Pitkänen,Ilkka T Miettinen,Karin Holmfeldt,Anna Pursiainen,Eila Torvinen

doi:10.3390/v13050928

Abstract

Bacteriophage control of harmful or pathogenic bacteria has aroused growing interest, largely due to the rise of antibiotic resistance. The objective of this study was to test phages as potential agents for the biocontrol of an opportunistic pathogen Pseudomonas aeruginosa in water. Two P. aeruginosa bacteriophages (vB_PaeM_V523 and vB_PaeM_V524) were isolated from wastewater and characterized physically and functionally. Genomic and morphological characterization showed that both were myoviruses within the Pbunavirus genus. Both had a similar latent period (50–55 min) and burst size (124–134 PFU/infected cell), whereas there was variation in the host range. In addition to these environmental phages, a commercial Pseudomonas phage, JG003 (DSM 19870), was also used in the biocontrol experiments. The biocontrol potential of the three phages in water was tested separately and together as a cocktail against two P. aeruginosa strains; PAO1 and the environmental strain 17V1507. With PAO1, all phages initially reduced the numbers of the bacterial host, with phage V523 being the most efficient (>2.4 log10 reduction). For the environmental P. aeruginosa strain (17V1507), only the phage JG003 caused a reduction (1.2 log10) compared to the control. The cocktail of three phages showed a slightly higher decrease in the level of the hosts compared to the use of individual phages. Although no synergistic effect was observed in the host reduction with the use of the phage cocktail, the cocktail-treated hosts did not appear to acquire resistance as rapidly as hosts treated with a single phage. The results of this study provide a significant step in the development of bacteriophage preparations for the control of pathogens and harmful microbes in water environments.

Highlights

The encouraging results obtained with the P. aeruginosa biocontrol in water emphasize the potential of using phages to control harmful bacteria
New control options are needed since antibiotic-resistant bacteria, such as multidrug-resistant P. aeruginosa, may spread in water environments and become a potential health threat if they are present in drinking water or recreational water such as in swimming pools and spas
Biocontrol in water may be sufficient to reduce the number of pathogenic bacteria below acceptable levels, at which there is no expected risk to health, and to inhibit their growth

Summary

Introduction

The control of harmful bacteria is an increasingly important and topical public health issue as antibiotic-resistant and disinfection-tolerant pathogenic strains become more common. Bacteriophages, which are viruses that exclusively infect bacteria, play an important role in biological processes by controlling the natural balance in an ecosystem, and hold great potential for targeting harmful bacteria. For biocontrol applications, promising candidates are broad-host-range lytic phages, which destroy the infected cell after immediate replication of the virion. One of the benefits of using bacteriophages over antibiotics or disinfectants is their specificity, i.e., they can target just the pathogenic bacteria of interest, rather than all bacteria. Bacteriophages have mainly been tested in clinical settings [1,2] and environmental applications are still rare. The interest in phages has recently increased, e.g., in agriculture [3], aquaculture [3,4] and the food industry [5,6,7]

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